Agenda Item: 8(d)
Prepared By: Jeffrey E. Poteet, General Manager, Water & Sewer
Business: Consent Agenda Item
Department: Water & Sewer
Subject:
Title
Approval of a Purchase Order Increase to Mississippi Lime Company for SM Hical Pebble Lime (CaO Pebble) for North Water Treatment Facility in the amount of $125,000 - Jeffrey E. Poteet, General Manager, Water & Sewer
Body
BACKGROUND:
The City previously approved a purchase order with Mississippi Lime Company for the supply of pebble lime used at the North Water Treatment Plant (NWTP). Pebble lime is an essential treatment chemical in the lime softening process, where it is converted to a lime slurry (calcium hydroxide) and added, along with aluminum sulfate (alum), to raw water in the reactor/clarifier. The addition of lime raises the water's pH, causing total organic carbon (TOC), color, hardness, and alkalinity to form nearly insoluble precipitates that settle to the bottom of the reactor/clarifier. The clarified water then proceeds through filtration, disinfection, and distribution. This process is critical to meeting state and federal drinking water standards and ensuring the safe, reliable operation of the City's potable water system.
The original purchase order was based on a contract price of $414.50 per ton. In accordance with the contract, the current renewal price increased to $446.84 per ton, an increase of approximately 7.8% due to supplier pricing adjustments and market conditions. In addition to the higher unit cost, pebble lime consumption has exceeded original projections.
The increased lime usage was driven by operational conditions associated with the Biological Aerated Filter (BAF) Improvement Project. During replacement of the North Water Treatment Plant's raw water pump, the plant operated almost exclusively on Aquifer Storage and Recovery (ASR) recovery water from December 28, 2025, through July 31, 2026. Unlike the plant's normal raw water source, ASR recovery water requires addit...
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