SAN JUAN, Puerto Rico -- During a two-week span in September of 2017, the small Caribbean Island of Puerto Rico was devastated by a colossal one-two punch from Mother Nature. Category 5 Hurricane Irma and Category 4 Hurricane Maria ravaged the American territory leaving many of its 3.4 million residents without shelter, food, water, and all without power.

The first storm, Irma, jabbed at the northern part of the island on Sept. 6, disrupting power to about one million people. As FEMA personnel and the many Emergency Support Function agencies, like the U.S. Army Corps of Engineers, mobilized and began recovery operations, they had to hunker down to ride out Hurricane Maria that arrived just 14 days after Irma. The second storm would deliver a knockout blow to the island's aging and fragile power grid.

"There wasn't an electric grid in the world that could survive the beating of a hurricane where there were registered winds of more than 200 miles per hour," said Engineer Justo Gonzales, Interim Executive Director, Puerto Rico Electric Power Authority.

The might of the storms weren't the only contributors to the grid loss. The system was designed with 75 percent of the electrical generation in the south feeding 70 percent of the Island's population in the north. This geography made the lines vital to transmission and distribution vulnerable. Additionally, years of inadequate maintenance and more recently, layoffs due to PREPA filing for bankruptcy in 2014 added to a disastrous mix that left islanders in the dark.

On September 21, the Puerto Rico Electric Power Authority reported near 100 percent of customers were without power, with the exception of facilities running on generators. Initial estimates revealed 80 percent of the 2,400 miles of transmission lines, 30,000 miles of distribution lines and 300 sub-stations were affected. The unprecedented damage led the U.S. Department of Energy to determine that normally-used methods of neighbor-state reinforcements would not alone handle the daunting task of restoring the Commonwealth's power grid.

Together, DOE, FEMA and the Corps determined about eight days into the response effort that the Corps was the right federal agency to lead the Power Restoration effort. With the FEMA mission assignment in hand, the Corps "took on the nation's toughest challenge: rebuild the grid in Puerto Rico," said Chief of Engineers Lt. Gen. Todd T. Semonite. "When Army Engineers are needed we don't back down, we rush to the point of the need."

Led initially by Col. John Lloyd, the Corps' Pittsburg District Commander, the Power Restoration Task Force quickly joined forces with the Department of Energy, FEMA, the Puerto Rican government and its Puerto Rican Electrical Power Authority to develop a holistic plan to assess damage, deliver immediate short-term power generation solutions and tackle the enormous challenge of restoring the grid system.

The overall approach was divided into three phases. Phase I focused on re-establishing the backbone of high-voltage transmission lines and providing spot generation at key public service nodes and population centers; Phase II expanded the line restoration to the lower-voltage distribution lines with a focus to additional population centers; and Phase III further expanding the reach of line restoration to outlying areas and includes the removal of many of the early-positioned spot generators.

"This restoration framework developed by the team in the early days of the effort has proven valuable throughout the on-going restoration process," said Col. Jason A. Kirk, commander, Task Force Power Restoration."

Task Force Power Restoration officially stood up on Oct. 11, 2017 and began by deploying 150 multi-discipline experts to Puerto Rico. Several days later, on Oct. 13, the Corps established offices in San Juan, Ceiba and Aguadilla. Additionally the Corps' Prime Power specialists from Delta Co. 249th Engineer Battalion arrived in Puerto Rico to begin repairs to distribution lines.

Delta 249th, comprised of all U.S. Army Reserve Soldiers, specializes in restoring overhead power distribution. The 249th arrived in Puerto Rico on Oct. 10, and from the start adapted their skills to the unique components of Puerto Rico's electrical system. The 249th Engineer Battalion (Prime Power) is a-one-of-a-kind power generation battalion assigned to the U.S. Army Corps of Engineers that provides commercial-level power to military units and federal relief organizations during full-spectrum operations.

"Learning the differences in this system was our biggest challenge but we quickly adapted to the needs for each situation," said Prime Power Overhead Distribution Specialist, Spec. Hunter Browning, from Preston, Connecticut. "We don't use very many concrete poles stateside and here we had to figure out how to set them to restore power to residential neighborhoods." Spec. Hunter and the Soldier/Electricians of the Cranston, Rhode Island-based D Company, 249th Engineer Battalion served in Puerto Rico until late December.

Five Lines of Effort

Beginning with the FEMA mission assignment to USACE, the goal of establishing grid stability and reliability would be accomplished by working along five lines of effort, temporary emergency power (spot generation at critical facilities), generation at power plants, grid materiel acquisition and distribution, reestablishing the grid's transmission "backbone" and repairing the grid's distribution lines.

Temporary Emergency Power

As the various agencies deployed across Puerto Rico to assess the power grid damage, the Albuquerque District Emergency Temporary Power Planning and Response Team (known as a PRT), one of seven in the Corps, worked with the U.S. Army 249th Engineer Battalion "Prime Power," along with contractor teammates to tackle the daunting mission of providing life-saving temporary power generation to critical facilities.

"The unprecedented damage to the power grid had put us in a situation we had never seen before," said Recovery Field Office Commander, Col. James DeLapp.

The PRT worked in response to FEMA's direction to quickly perform power assessments and generator installations. By Oct. 28, 2017, the team would break the previous mark of 310 generators installed set during the Hurricane Katrina response efforts in 2005. By the end of October the team would reach 366 generators installed, averaging approximately twenty installations a day.

"At that rate, we would easily double the installation numbers of the previous record. The big difference was these generators would likely be in place for months," said DeLapp. "As we continued to make strides in repairing grid power, the Emergency Temporary Power PRT dedicated itself to providing generator power to those cities and towns until there was no need for temporary power generation," said DeLapp.

In addition to the Albuquerque PRT, at the request of Puerto Rico Governor Ricardo Rosselló, FEMA tasked the Corps to maintain and repair non-federally installed generators. USACE Headquarters deployed the Honolulu District Temporary Emergency Power PRT to take on this new mission.

"The goal for the supplementary temporary power mission is to repair and maintain the facility owned, permanently installed generator to prevent the requirement for a FEMA provided generator or to allow an already installed FEMA provided generator to be de-installed from the facility and used for other critical needs," said Jackie Conant, mission liaison.

Unlike the traditional Temporary Emergency Power mission, which installs FEMA provided generators from a pre-determined list of manufacturers, the "Non-Fed" team had to be prepared to service, maintain and repair generators from all makes, models, sizes, and ages.

At the height of the Temporary Emergency Power operations, the Corps installed more than 1,600 power generators.

"This was a unique, never been done before, mission with a variety of challenges," said DeLapp. "There are generators in use that are no longer being made, one generator that we repaired was almost 60 years old."

Power plant generation

The second line of effort was to support PREPA in ensuring adequate generation was available from Puerto Rico's power plants. PREPA asked for the Corps' assistance to bolster and stabilize output from the Palo Seco and Yabucoa power plants.

For Palo Seco, TF Power accomplished this mission by leasing and installing two 33-megawatt generators.

"This move provided load balancing capability in the Greater San Juan area which was critical to supporting PREPA's priority of effort in the San Juan metropolitan area-home to almost two million of Puerto Rico's 3.4 million citizens," said Kirk.

On Oct. 9, 2017, TF Power teamed with the Corps' Omaha District to award a contract for $35.1 million dollars to Weston Solutions, based out of West Chester, Pennsylvania to provide this initial critical step in what would be the first of a series of major contracts toward the repair of the power grid in Puerto Rico.

TF Power awarded an additional $19 million contract on Nov. 6, 2017 to Aptim Federal Services, LLC, of Alexandria, Virginia for the installation of a 25 megawatt generator at the Yabucoa Power Plant to provide more reliable power to the Yabucoa and Humacao areas, located in southeast Puerto Rico.

"The supplement of power via our Corps-provided mega-generators at PREPA's Palo Seco and Yabucoa power plants has been critical throughout this effort to provide much-needed capacity to the damaged grid," said Tim Gouger, program manager for mega-mobile power generation systems and volunteer from USACE's Omaha District.

Restoring the Transmission "Backbone"

The other integral part to providing grid stability and reliability was through the restoration of the central Puerto Rico transmission loop in order to link power generation hubs in the north (San Juan) and south (Ponce and Guayama) as well as providing initiation of repairs to the distribution system in the San Juan and Mayaguez regions. TF Power worked with USACE's Huntsville Engineering and Support Center and the Jacksonville District to award the two Grid Repair contracts that would provide the utility field workers essential to execute repair and restoration of the severely degraded grid.

On October 16th, Huntsville Center awarded a grid repair contract to Irving, Texas-based Fluor Corporation. On October 19th, Jacksonville awarded a grid repair contract to Atlanta, Georgia-based PowerSecure, Inc. In late October and early November, these Corps contract teammates began arriving in Puerto Rico to initially assess and quickly begin the monumental task of grid repair.

Microgrids

Early on in Phase I it was identified that several of the hardest hit areas would not be reached to restore their transmission and distribution lines which led engineers to explore many options. One was the use of microgrid technology to temporarily power areas that were hit hardest by Hurricane Maria.

"A microgrid can take many forms," said Capt. Aaron Anderson, operations officer with TF Power Restoration. "We are taking one or more 1,850 kilowatt generators, the huge ones you find powering hospitals and big box stores, and with the use of transformers, set up at a site. We then hook directly into PREPA infrastructure through a substation or directly into the main grid, and push power to a variety of facilities that are on the line that haven't been damaged and can accept it."

In total, Anderson's team set up microgrids in nine locations, starting with Culebra Island. The next six were placed in the southeast part of the island, which sustained tremendous damage when Hurricane Maria made landfall. Currently microgrids are providing power to citizens in Arecibo, Maunabo, Culebra, Villalba and Lares. Microgrids in Pattillas, Naguabo, Yabucoa and Humacao have been shut down and removed from the grid.

Microgrids are not a plug and play solution, assessments had to be completed in order to make sure the grid was good enough to accept power and what types of facilities were being powered on that system. Only then are semi-trailer-sized generators connecter to the grid. The microgrid initiative allowed for the Task Force to do multiple things: get power quickly and more efficiently to a lot of homes, businesses, and critical facilities, but it also allowed for a look at facilities down range that were running on smaller generators.

Anderson said they were able to reclaim those generators and put them where needed. Using two large generators on a microgrid configuration, would allow for the repurposing of eight to 10 smaller ones. "Throughout this mission, PREPA has been a great partner. They're 110 percent behind this initiative," said Anderson. "It's their system, so we have the ability to put the microgrid in place and install the transformers, and when we go from our system into theirs, PREPA performs those connections. So they are fully on board. They also provide the operators for the system."

It's hard to determine the exact amount of people who have their power restored through microgrids, said Anderson.

"Looking at the population of five towns where we've installed the microgrids, we estimated we served about 95,000 people," said Anderson. "That doesn't mean 95,000 people necessarily have power; now their town has power. The aim is that their grocery store now has power; they now have a town emergency center that can issue them assistance; 95,000 people are going to directly benefit from the microgrids."

Restoring lines

The Task Force would quickly discover that communication and unity of effort would be critical to organizing the multiple entities deployed to support power restoration across the island. To better enable partnered restoration alongside PREPA. This gave way to the Task Force relocating to PREPA headquarters on October 28, "in order to optimize communication and collaboration efforts," said Col. Lloyd.

System redundancy and Population centers

Phase II included continuing to establish system redundancy and restoring access to power to major population centers. Reestablishing transmission and distribution lines by providing temporary repairs allowed lines to be energized aiding in stability and system redundancy. The goal was to restore the distribution capabilities in the regions of Arecibo, Bayamon, Caguas, Carolina and Ponce to 95 percent.

In this phase the transmission lines to key industry sectors were restored near Juncos, Dagaou and Humacao. Concurrently distribution crews continue to build on established transmission lines to connect loads to the system and restore power to end users.

"This is where the bulk of the Corps contracting capacity contributed, with Fluor and PowerSecure line crews restoring transmission (230 kilovolt), sub transmission (115 kilovolt) and distribution (38 kilovolt) lines all the way to the customer," said Kirk. "The USACE effort covers almost 40 percent of the restoration efforts with PREPA and Industry partners carrying out the remaining 60 percent."

In order to accomplish Phase II goals USACE increased the PowerSecure contract by $350 million for a total of $390 million and increased Fluor's contract to a combined $746 million. The increases in funding would speed power restoration work by bringing additional people, equipment and materials to the effort to repair hurricane-damaged transmission and distribution lines, connecting them to power plants in San Juan, Mayaguez, Ponce, Bayamon, Carolina and Arecibo.

Location and logistics

Two major challenges to restoring the electrical grid involved sourcing of materials and equipment and, the movement of that equipment to the Caribbean island. Hurricane Maria's damage to Puerto Rico's ports, airfields, roads, bridges, electric grid and communications had slowed initial assistance efforts but conditions and the pace of recovery continued improving.

"Natural disasters in the continental United States had depleted supplies, and the geographical separation of the island limited transport to slow barges and air transport, which could not be used for shipping the larger materials like power poles," said Frank Ford, Officer in Charge of Task Force Power Restoration Materials Section. "Unlike a stateside disaster response, no railroad or over the road trucking was available for delivering materials to the island."

On Oct. 10, 2018, USACE placed an initial order of $115 million for materials including more than 50,000 utility poles and 6,500 miles of cable. In some cases materials had to be manufactured then mobilized, loaded, floated or flown, downloaded and distributed.

For the high demand, large quantity items, TF Power Restoration used the Defense Logistics Agency strategic purchasing platform as its purchasing agent. In all of these purchases, the Task Force worked with the PREPA technical specification engineers to ensure all materials were technically acceptable and compatible with the PREPA electrical power system.

On November 3, the USNS Brittin, Military Sealift Command, arrived at the Rafael Cordero Santiago Port of Américas in Ponce with a FEMA funded shipment of relief supplies focused on USACE equipment for the power restoration mission. The supplies included 300 mobile generators, 43 bucket trucks, 33 digger derricks, a UH-60 Blackhawk helicopter and 287 pieces of rolling stock for power generation. The Brittin would return with an additional shipment on November 20.

Manufacturers fabricated supplies as quickly as possible and, as the needed materials were fabricated, they were expedited to Puerto Rico. USACE and PREPA have also utilized partnerships with industry to order supplies from their inventory. Ordering transformers was a prime example of this partnership.

Grid restoration required an estimated 6,234 transformers but, due to supply shortages that seemed to be a difficult challenge to overcome. In February, Industry partners stepped in and agreed to expedite, via air, the delivery of 2,600 transformers from their inventories to bolster PREPA's 1,000 transformers from local warehouses.

USACE had also invested in the local economy by purchasing 2,100 power poles from Power Precast Products Corp. and Moca Concrete Poles, Inc. The first shipment of precast concrete poles valued at $45,000 was received on Nov. 9 from Power Precast Products. The vendor is providing 180 or more poles on a weekly basis to supply power restoration efforts.

Most power restoration material on the island is received by barge at either Port of San Juan or Port of Ponce where it is inventoried within 24 hours of arrival and is available for pickup by the contractor. Most material is picked up with 24-48 hours and placed into the field for contractor use.

"The ability to quickly and efficiently acquire, ship, receive, and distribute critical repair parts across the island has been the lynchpin of our mission success to date," said TF Power Restoration Deputy Commander Lt. Col. Cullen Jones.

To date, BoM Squad has received 4,657,563 pieces of material (approximately 49,133 poles and 4,242 miles of conductor wire) and the Defense Logistics Agency has executed $222.95M in purchases. During the time between February 27, and March 12, DLA and U.S. Transportation Command will delivered an additional 8,023,691 pieces of material.

"As our mission transitions, the BoM squad will also execute the critical responsible transfer of repair inventory to PREPA as they push past the emergency repairs conducted during the federal response towards full restoration, stated Jones."

The last mile

The final phase of the Task Force Power Restoration mission restores grid power to the remaining five percent of people in the more remote and challenging areas with the goal of restoring the system to fully operational status.

"This phase will be primarily executed by PREPA crew and their contractors, with the assistance from investor owned utilities," said Kirk. "USACE will continue to distribute, account for and transfer materials as it is essential for a responsible closeout."

"The Corps' Emergency Management mission is hands-down the most fulfilling of our many diverse missions - the ability to directly contribute to the well-being of our fellow citizens is an honor and privilege," said Col. Jason Kirk who served as the second Task Force Power commander. "In Spanish I tell folks: Me siento honrado de servir Puerto Rico-my honor to serve Puerto Rico and to lead the Task Force that has included 800-plus civil servant volunteers who have worked extremely hard executing this critical mission to turn the lights on and deliver reliable power to the U.S. citizens of Puerto Rico.

Writers note: On March 23, 2018, Task Force Power Restoration reached 93.63 percent power restored to the people of Puerto Rico.

Others contributed to this article.