THIRD LIME SLAKER AT WATER TREATMENT PLANT
PROFESSIONAL SERVICES AGREEMENT FOR DESIGN
The Ames Water Treatment Plant uses pebble lime in the treatment process to soften the water. The lime is mixed with water in lime slakers. The original design of the facility included three lime slakers. The middle slaker was intended to provide important redundancy, as it could accept pebble lime from either of the two overhead lime storage bins, and would be able to discharge to either of the two lime slurry aging tanks on the ground floor below.
When the estimated construction costs for the new plant exceeded the planned budget, staff worked with the consultants to identify elements that could be delayed without adversely affecting the immediate operation of the new plant. The third slaker was one of the deferred elements.
The batch lime slaking system uses proprietary equipment provided by RDP Technologies, Inc. The system is unique in that it can be highly automated, which was seen as desirable following the labor intensive nature of the paste slakers used at the old plant. Ames was one of the first large installations of the RDP batch slakers, and the manufacturer continues to use Ames in its marketing efforts due in large part to staff's satisfaction with its performance.
Because of the nature of the slaking operation it would be nearly impossible to incorporate a new slaker from a different manufacturer into the existing operation. The City's Purchasing Policies include provisions for "single source negotiations" when there is only one practical source for the goods or service to be procured. For the design services of the new slaker, staff is utilizing that single source provision and recommending that the design be performed by Strand Associates.
The original design for the Water Plant was performed by FOX Engineering, which subsequently merged with Strand. The original engineer is still with Strand, allowing better continuity with the original design concepts and intent. Additionally, Strand has the original design files and drawings that includes the original preliminary design of the middle slaker, greatly reducing the cost compared to having a different consultant start over with new drawings.
Strand has provided a proposal to perform the design of the new slaker. For this project, staff will be recommending that the third slaker be provided by RDP through a negotiated procurement. This approach provides a significant reduction in the design labor required since the design can be based on a single piece of equipment, as opposed to needing to accommodate multiple manufacturers.
Strand will be working directly with RDP to finalize the details of the new equipment and preparing specifications for the installation of the equipment and the electrical, plumbing, compressed air, and mechanical connections. They will also assist City staff by preparing a controls description so that staff can integrate the new slaker into the SCADA system. They will also be coordinating with the Iowa DNR on all required design reviews and construction permits. The design work is expected to take roughly four months.
The project is budgeted as carryover funds from the FY 2025/26 budget (Water Plant Facility Improvements Project) in the amount of $873,000. The budget included an allowance for engineering of $84,000. The proposal from Strand for design is $69,900.
- Approve the use of a single source negotiation for engineering services and approve the professional services agreement with Strand Associates for the addition of a third lime slaker at the Ames Water Plant in the lump sum amount of $69,900.
- Do not approve the use of single source negotiation for engineering services and direct staff to utilize a formal Request for Proposals from additional engineering firms.
- Take no action on the project at this time.
The City's adopted Purchasing Policies and Procedures includes a provision for negotiating with a vendor "...when there is only one practical source for the equipment, material, or service." In this case, Strand was the original engineer for the existing equipment and has all of the drawings and models for the Ames Water Plant. The Purchasing Department has approved the use of a single source procurement. The negotiated scope of work and contract language has been reviewed and is acceptable. Therefore, it is the recommendation of the City Manager that the City Council adopt Alternative #1 above.