Attachment_1_-_SOW_-_Pompey_s_Pillar_Tank_Replacement.pdf
PDF 103 KB Posted
- Attached to
- Pompey's Pillar Iron Filter Tanks Federal contract opportunity
- Solicitation number
- 140L3626Q0023
About this file
This is a Statement of Work for the replacement and rehabilitation of iron filtration equipment at the Pompey's Pillar drinking water treatment facility, scheduled for April 2026.
The work scope addresses deficiencies identified by the Montana Department of Environmental Quality, requiring removal and replacement of three existing iron filtration units, replacement of exhausted filter media, rehabilitation of treatment components, and system reactivation. Current conditions show inadequate iron and manganese removal, with manganese concentrations measured at 0.552 mg/L at the clearwell effluent (versus a recommended 0.05 mg/L) and iron concentrations up to 0.10 mg/L. The filter vessels have never been re-bedded, and two HP-9 hydropneumatic tanks are waterlogged and non-functional. System reactivation will include startup procedures, verification of aeration and backwash functionality, air eductor adjustments, and confirmatory sampling to ensure compliance.
The specifications require three pressure iron filter tanks designed for potable water use, NSF/ANSI 61 certified, sized for existing system flow and pressure requirements, with epoxy-lined steel or fiberglass reinforced plastic (FRP) construction and 100–150 psi pressure ratings. Two replacement hydropneumatic pressure tanks (bladder or diaphragm type preferred) must be NSF/ANSI 61 certified, pre-charged with captive air design, and sized to meet system demand and minimize pump cycling. All tanks require manufacturer certifications, pressure testing documentation, and coordination with existing piping to minimize modifications.
View the file
Other files for this federal contract opportunity
| File | Type | Posted |
|---|---|---|
| Sol_140L3626Q0023_Amd_0003.pdf | ||
| Attachment_4_-_Water_System_Submittal_0003.pdf | ||
| Attachment_3_-_Pompeys_Water_System_0003.docx | DOCX document | |
| Sol_140L3626Q0023_Amd_0002.pdf | ||
| Sol_140L3626Q0023_Amd_0001.pdf | ||
| Sol_140L3626Q0023.pdf | ||
| Attachment_2_-_Wage_Determination.pdf |
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Text version
Statement of Work Pompey’s Pillar Iron Filter, Media, and Tank Replacement
April 2026
Background:
The proposed work includes the removal and replacement of three existing iron filtration units, replacement of exhausted filter media, rehabilitation of associated treatment components, and reactivation of the system to restore proper operation of the drinking water facility. This work is directly supported by a deficiency identified by the Montana Department of Environmental Quality (DEQ), which determined that the treatment plant is not operating as designed due to unmaintained and underperforming equipment.
The system was originally designed to remove iron through aeration followed by treatment in three pressure sand filters, with subsequent chlorination prior to entering the clearwell. Current conditions indicate that the iron and manganese removal processes are not functioning effectively. Field observations identified visible iron and substantial manganese precipitate accumulation within the storage tank and in downstream cartridge filtration located after the clearwell and prior to distribution. Analytical results further confirm treatment deficiencies, with manganese concentrations measured at 0.552 mg/L at the clearwell effluent - well above the recommended level of 0.05 mg/L - and 0.074 mg/L at the entry point to the system. Iron concentrations have been measured up to 0.10 mg/L. In addition, there is no documented record indicating that the filter vessels have ever been re-bedded, limited understanding of backwash procedures, and no available information regarding the air eductor settings necessary to achieve proper oxidation. As a result of ineffective iron and manganese removal, chlorine demand has become inconsistent, leading to variable and unreliable disinfectant residuals.
The HP-9 hydropneumatic tanks also appear to be waterlogged and are not functioning as intended. These captive air tanks are designed to maintain an appropriate air-to-water ratio to facilitate oxidation and gas release; however, both tanks exhibited a full or “waterlogged” condition when field-tested, indicating loss of air charge. Compromised hydropneumatic tanks are unable to provide adequate pressure control and may create conditions conducive to bacterial growth due to stagnant water and accumulated sediment.
Replacement of the iron filters and associated media, along with evaluation and rehabilitation or replacement of the hydropneumatic tanks, is necessary to restore proper treatment performance.
Reactivation of the system will include startup procedures, verification of aeration and backwash functionality, adjustment of air eductor settings, and confirmatory sampling to ensure treatment objectives and regulatory requirements are met. This work is justified to correct DEQ-identified deficiencies, restore the system to its intended design performance, stabilize disinfection, protect public health, and ensure reliable, compliant operation of the water treatment system moving forward.
Specifications:
Tank Materials List
1. Iron Filter Vessels (Replacement)
(3) Pressure iron filter tanks/vessels o Designed for potable water use o Sized to meet existing system flow and pressure requirements o NSF/ANSI 61 certified (or approved equal) o Construction: epoxy-lined steel or fiberglass reinforced plastic (FRP) o Pressure rating: typically 100–150 psi (or as required by system design)
Interior coating (for steel tanks) suitable for corrosion protection and drinking water service
2. Hydropneumatic Tanks (Replacement)
(2) Hydropneumatic pressure tanks (bladder or diaphragm type preferred) o Sized to meet system demand and minimize pump cycling o NSF/ANSI 61 certified for potable water systems o Pre-charged captive air design o Rated for system pressure and operating conditions
Factory-applied internal lining suitable for potable water
General Notes
All tanks shall be compatible with the existing treatment system and site conditions.
Tanks shall include manufacturer certifications and pressure testing documentation.
Connections and dimensions shall be coordinated with existing piping to minimize modifications.
File details come from the government source that posted it. Updated .