WATER TREATMENT PLANT LIME SLUDGE DISPOSAL CONTRACT
The City's Water Treatment Plant (WTP) is a conventional lime-softening facility that generates lime sludge as a byproduct of the lime softening process. The lime sludge consists primarily of calcium carbonate and magnesium hydroxide, which is dewatered and stored in lagoons prior to being applied on agricultural ground as a soil conditioner. To maintain adequate storage for the lime sludge, the material must be removed from the lagoons annually.
On April 25, 2023, City Council awarded a contract to Wulfekuhle Injection and Pumping, Inc. of Peosta, Iowa for the removal and disposal of lime sludge. The contract calls for the removal of 26,000 wet tons of lime at a unit cost of $14.89 per wet ton, plus mobilization charges of $5,000, for a total contract price of $392,140. The contract is renewable annually for a total of five years, dependent on successful performance by the contractor each year. The contract unit prices are fixed for the entire five-year agreement.
Work performed under Year Three of the agreement has been completed. Wulfekuhle disposed of 19,988.95 wet tons for a total contract price of $302,635.49. The work is completed and is ready for Council acceptance.
The City Council is also being asked to award the fourth year of the agreement to Wulfekuhle Injection and Pumping Inc. in an amount not to exceed $392,140 for FY 2026/27 (contract period July 1, 2026 – June 30, 2027). Funding for this contract is outlined in the table below:
| FY 2026/27 Contract | Expenses | Funding Source |
| Mobilization | $5,000 | |
| Lime Sludge Disposal (26,000 wet tons) | $387,140 | |
| FY 2026/27 Water Treatment Operating Budget | $392,140 | |
| TOTAL | $392,140 | $392,140 |
Award for future renewal years will be brought to Council annually and will be subject to the contractor's acceptable ongoing performance, the proposed cost increase, and the annual allocation of sufficient funds.
- The City Council can:
- Accept completion of the year three contract (FY 2025/26) for lime sludge disposal with Wulfekuhle Injection and Pumping of Peosta, IA in the final amount of $302,635.49.
- Award contract to Wulfekuhle Injection and Pumping Inc. of Peosta, IA for FY 2026/27 (Year Four) lime sludge disposal service in the amount of $392,140.
- Accept completion of the year three contract (FY 2025/26) for lime sludge disposal with Wulfekuhle Injection and Pumping of Peosta, IA in the final amount of $302,635.49.
- Reject bids and direct staff to solicit new bids for lime sludge disposal.
- Reject bids and direct staff to pursue landfilling of the lime sludge in lieu of land application.
Wulfekuhle Injection and Pumping, Inc. has completed the FY 2025/26 lime sludge disposal contract, and an Engineer's Statement of Completion has been received (attached). The original bid included the option to extend the agreement for up to five years, on a year-to-year basis. Staff is satisfied with the performance of the contractor to date and is recommending that a fourth year be awarded at the same unit cost as FY 2025/26. Therefore, it is the recommendation of the City Manager that the City Council adopt Alternative No. 1 as stated above.