A1 SOW Final _20MAY25 0201_A_TAO187-SWI-CLEAN AND GAS FREE TANKS VOIDS COFFERDAMS.docx

1.0 ABSTRACT

This item describes the requirements for the contractor to open, clean, gas-free, maintain, fill, and close miscellaneous tanks, voids, cofferdams, and spaces.

2.0 REFERENCES/ENCLOSURES

2.1 References

2.1.1 NAVSEA Drawing No. 801-8386102, Booklet of General Plans, USNS BIG HORN (T-AO 198)

2.1.2 NAVSEA Drawing No. 835-6580174, USNS BIG HORN, Trim & Stability Booklet

2.2 Enclosures

2.2.1 USNS BIG HORN (T-AO 198) List of Applicable Tanks, Voids and Cofferdams to be Opened during Current Availability

2.2.2 MARAD MA-496 Instructions for Vessel Entry Into The National Defense Reserve Fleet (NDRF)

3.0 ITEM LOCATION/DESCRIPTION

3.1 Location/Quantity: See Enclosure 2.2.1

4.0 GOVERNMENT FURNISHED EQUIPMENT/MATERIAL/SERVICES: None

5.0 NOTES

5.1 The contractor and all subcontractors, regardless of tier must consult the General Technical Requirements (GTR) to USNS Big Horn

( TAO 187 198 )

GENERAL SERVICES AND REQUIREMENTS – Statement of Work

CONTRACT NO. N00000-00-X-0000

ITEM NO. 0201

CATEGORY "A"

2025-04-23 TAO187-SWI-CLEAN AND GAS FREE TANKS VOIDS COFFERDAMS AND SPACES (SINGLE HULL ONLY) Scott Drew

0021A - 3 determine applicability to this work item. In performance of this work item, the contractor and all subcontractors regardless of tier must comply with all applicable GTR requirements.

5.2 The contractor and all subcontractors, regardless of tier are advised to review other work items under this contract to determine their effect on the work required under this work item.

6.0 QUALITY ASSURANCE REQUIREMENTS

6.1 Tank coating system conditions shall be identified and documented by the contractor during tank surveys as directed by the OMT REP. ABS surveyor shall receive a copy of contractor’s reports.

7.0 STATEMENT OF WORK REQUIRED

7.1.1 Note: The vessel was involved in a recent marine grounding incident and has temporary structural repairs through the vessel. The repairs are primarily in tanks and the propulsion/steering running gear systems. Sensitivity for the temporary repairs shall be considered when executing this statement of work.

7.2 The OMT REP and MSC Naval Architect will assist contractor with ship loading documents and software. The contractor shall utilize the services of a naval architect or structural engineer to support this planning. The contractor shall provide their tank unloading plan to the OMT REP at least two business days prior to starting this work to permit review and approval by MSC Naval Architect.

7.3 Contractor shall on arrival at the contractor’s facility take, record, and verify soundings of all tanks listed in Enclosure 2.2.1, using References 2.1.1 and 2.1.2 as guidance. The OMT REP shall review and endorse all soundings taken/recorded. Submit copy of endorsed record to the OMT REP.

7.4 Accomplish the following for each tank/space listed in Enclosure 2.2.1:

7.4.1 Open manholes and erect/maintain safety guards over openings.

7.4.2 Temporarily provide blowers and ventilate tanks and spaces, inclusive of confined areas around manhole covers.

a. Ventilation of the tanks shall be accomplished so as to prevent tank fumes from exhausting in the interior compartments of the ship.

7.4.3 Temporarily provide and maintain, as required, tank lamping/lighting. Lighting shall be explosion proof, safety type lights.

7.5 The contractor is to provide the services of a Marine Chemist in support all gas free certificate requirements.

7.5.1 Clean and Gas Free tanks and spaces listed in Enclosure 2.2.1. Cleaning shall completely remove all traces of dirt, sludge, debris and liquids. Clean and Gas Free tanks and spaces listed in Enclosure 2.2.1.

7.5.2 Where a battery of tanks is designated for gas freeing, all interior spaces in way of same, such as cofferdams, voids, bilges, bilge wells and other spaces, even if not specifically mentioned, shall be considered as being included as spaces to be cleaned and gas freed.

7.5.3 For all tanks and spaces indicated in enclosure 2.2.1, air vents, sounding tubes, filling and suction lines and other appurtenances shall be included for cleaning and gas freeing. Secondary manhole covers for each tank shall also be opened.

7.5.4 Post original gas free certification at each tank/space location. Certificate shall be mounted directly at the tank/space manhole entrance.

7.5.5 Post copy of gas free certificates at the designated gangway access to the vessel. Certifications posted at gangway shall be in a protective weather/waterproof enclosure that is accessible and visible.

7.6 Surveys and testing requirements for these tanks shall be addressed via the OMT REP and attending MSCHQ Naval Architects.

7.7 At the conclusion of all required work, conduct a final closeout inspection for each tank/space listed in enclosure 2.2.1 with the OMT REP. No tank shall be closed until a final inspection is accomplished with the OMT REP in attendance.

7.7.1 Ensure all blowers, lighting, staging, tools, and miscellaneous equipment are removed prior to the final inspection. Any staging necessary for OMT REP close out inspection shall be removed just prior to final acceptance close out of tank/space.

7.8 Upon acceptance of final closeout inspection and by direction of the OMT REP, reinstall manhole covers using new gaskets, grommets, and wicking. Submit a condition found report for any missing or damaged fasteners or hardware.

7.9 The tanks and spaces included in Enclosure 2.2.1, shall be opened and prepared for gas free certification within (10) days of the shipyard availability start.

8.0 GENERAL REQUIREMENTS:

Enclosure 2.2.1 – USNS BIG HORN (T-AO 198) List of Applicable Tanks, Voids and Cofferdams to be opened during Current Availability

Cargo Oil (DFM) Tanks

Description

Tank Location

(gallons)

No. 7 CTR DFM/JP-5 Cargo Tank

(5-43-0)

666,419

Grout cement – Approximately 500 gallons

666,419

Grout cement – empty tank

No. 10 CTR JP-5 Cargo tank

Grout cement – empty tank

USNS Big Horn

( TAO 187 198 )

GENERAL SERVICES AND REQUIREMENTS

CONTRACT NO. N00000-00-X-0000

ITEM NO. 0021A

CATEGORY "A"

2025-04-23 TAO187-SWI-CLEAN AND GAS FREE TANKS VOIDS COFFERDAMS AND SPACES (SINGLE HULL ONLY) Scott Drew

0021A - 9

Fuel Oil Tanks

100% Capacity (gals)

Area (sqft) Arrival Condition (gallons)

(P) & (S) Grout cement – Empty Tank

Grout cement – empty tank

Lube Oil and Settling Tanks

100% Capacity (gals)

Area (sqft) Arrival Condition (gallons)

Grout cement – Empty Tank

Miscellaneous Tanks

100% Capacity (gals)

Area (sqft) Arrival Condition (gallons)

Grout cement – empty tank

Enclosure 2.2.2 – USNS BIG HORN (T-AO 198) MARAD MA-496 Instructions for Vessel Entry into the National Defense Reserve Fleet (NDRF)

5.12 WATER TANKS. All potable and fresh water tanks shall be pumped dry unless otherwise directed. All liquid ballast, not essential for trim or stability, shall be removed. Where ballast is left aboard, watertight blanking shall be installed. All water ballast aboard shall be fresh dock water (non-river). Where tanks are not emptied, they shall be pressed to limit free air space. MARAD shall be consulted regarding amount and retention of water ballast required for stability purposes prior to Fleet entry.

5.13 CARGO TANKS. Cargo tanks shall be thoroughly stripped cleaned and certified as gas free before arrival at the Fleet site. A gas free certificate shall be properly posted with a copy provided to Fleet staff. Tankers offered for lay-up shall have all cargo tanks, pump rooms, and pipelines gas freed with a gas free certificate properly posted.