REPAIRS TO ELEVATED WATER STORAGE TANK FACILITY, DIEGO GARCIA

REPAIRS TO ELEVATED WATER STORAGE TANK FACILITY #1504 – U.S. NAVAL SUPPORT FACILITY, DIEGO GARCIA, BRITISH INDIAN OCEAN TERRITORY (B.I.O.T.)

PROJECT DESCRIPTION:

The U.S. Navy Support Facility (NSF) Diego Garcia is located in the Indian Ocean within the British Indian Ocean Territory (B.I.O.T.). NSF Diego Garcia is located south of equator approximately 2900 kilometers southwest of Bombay, India and approximately 2400 kilometers northeast of Mauritius, 4,723 km west-northwest of the west coast of Australia, and approximately 8,906 kilometers southwest of Guam.

Diego Garcia is a narrow coral atoll, is the largest of the 60 small islands comprising the Chagos Archipelago, being an atoll occupying approximately 174 square kilometers, of which 27.19 square kilometers is dry land. The coral atoll is horseshoe-shaped giving it the nickname “Footprint of Freedom” with an opening approximately 6.4 kilometers wide where the lagoon transitions into the Indian Ocean. The land distance from tip to tip of the atoll is 64 kilometers, enclosing a lagoon 21 kilometers long and up to 11 kilometers wide. The total land area is approximately 2720 hectares. Grade elevations on the atoll range between one to nine meters above Mean Sea Level (MSL) with an average elevation of 1.8 meters MSL.

Project Scope: The Design-Build Repairs to Elevated Water Storage Tank project provided repairs to the existing 150,000-gallon elevated water storage tank, Facility 1504, based on the recommended reports “Evaluation of the 150,000 Gallon Steel Elevated Water Tank F1504, Naval Support Facility Diego Garcia, B.I.O.T.”, prepared by Tank Industry Consultants (TIC) for NAVFAC Far East.  The contracted scope of work required the repair of structural deficiencies due to corrosion and metal losses on the tank, riser, and tower structural components including columns, diagonal bracing rods, riser rods, struts and all associated connections, deficiencies on concrete foundations due to cracking and spalling. Repaired the existing ladders, balcony, roof platforms and entry manholes on the riser and tank roof in compliance with ANSI/OSHA.  Repaired the operational deficiencies of the tank’s sanitary condition in compliance with AWWA. Repair of the tank’s structural components involving replacement in part or in whole. Provided a new energy and maintenance efficient obstruction lighting system, cathodic protection system, and lightning protection system, replaced with a new level-indicating device and its associated components, and a new transducer for SCADA level monitoring connected to the existing SCADA system. The work also included the removal of paint containing lead, cadmium, chromium, and other paint-related work including surface preparation, replaced components, and installed enclosure to contain hazardous materials from spreading into the surrounding areas due to sandblasting work. All hazardous waste materials were contained and were transported for disposal off-island. Disinfected the water storage tank after the completion of the repaired work.

Several Notable features of work included:

• The repair of the elevated tank structure involved the removal of secondary structural members with correct planning, methodology, sequence of work, and analysis of construction loads carefully considered to prevent structural overload to the structure.
• The repair of the tank and its structure included modifications of structural components identified for the replacement to comply with present structural codes and standards.
• Provided the best management practices to address site-specific conditions for corrosion and metal losses on the tank and its structure.
• Installed multi-level scaffoldings from the ground up to the rooftop of the tank and dismantled the scaffoldings level by level from the rooftop of the tank down to the ground level.
• Installed phase-by-phase lead-abatement containment supervised, inspected and approved by the Certified Industrial Hygienist.

• Deployed a Certified Industrial Hygienist to conduct inspections before and after removal of lead-containing paint, sandblasting activity, and trained workers for Lead in Construction awareness.
• Performed the repair with compliance to safety requirements concerning work at elevated structures eliminating the danger to workers and the surrounding personnel and properties.
• Performed removal of lead-containing paint in compliance with all environmental requirements with extreme care initiated to avoid exposure of adjacent areas to hazardous materials removed.
• Overcame difficulties of inevitable high wind, unforeseen thunderstorms especially when working on sandblasting and coating.
• The geographical location of the project in Diego Garcia exposed the project to severe weather conditions year-round.

Due to the onset of the Covid-19 pandemic and the implementation of Restriction of Movement for inbound personnel, the Special Inspector was unable to travel to Diego Garcia however, virtual inspections were conducted for the remaining duration of the project.

Owner:
U.S. Department of the Navy

Contract No.:
N40084-18-D-0066
Task Order N40084-18-F-4396

Original Contract Amount:
$3,725,050.00

Final Contract Amount:
$3,725,050.00

Original Contract Completion Date:
December 26, 2019

Final Contract Completion Date:
August 11, 2021

Actual Date Contract Accepted:
May 18, 2018

Start Date:
May 18, 2018

Was Offeror Prime Contractor or Subcontractor:
Prime

Percentage of Work Performed:
80%

Liquidated Damages Assessed:
None

Project Manager:
Rene A. Bautista

Customer Evaluation:
None