Category: Forensic Engineering

Hurricane Shelter Collapse

Haag Engineering was asked to determine the cause of collapse of a hurricane shelter, determine responsible party with respect to subrogation, & evaluate the remaining structure with respect to repairability.

The metal building structure was an indoor sport/event arena that doubled as a hurricane shelter.  Approximately 1,400 people had flocked to the shelter for safety before the storm.  The metal roof system peeled away as the storm neared, causing most of the building to collapse.  All 1,400 occupants survived due to their retreat below the concrete bleachers.  Haag Forensic Engineers were called out to determine the primary cause of the collapse, determine who was responsible with respect to subrogation, and to evaluate the remaining structure with respect to reparability.  We examined the structure, stewarded required evidence retained for all parties, and identified building conditions that led to the collapse.  Our conclusions were provided via open forum presentation during mediation.  The accuracy, detail, and reporting of our conclusions in a simple yet complete presentation enabled all parties to quickly understand the facts of the collapse and come to a mutual financial agreement without litigation.  The structure was reconstructed after settlement was achieved.

Hyatt Regency Walkway Collapse

Hyatt-Case-Study

Haag Engineer E. Earle Walters discusses the investigation of the collapse of two walkways at a Hyatt Regency hotel.

Haag Engineer E. Earle Walters discusses the investigation of the collapse of two walkways at a Hyatt Regency hotel.

Imperial Sugar- Sugar Dust Explosion and Fire

imperial-case-study

A massive explosion and ensuing fire destroyed much of the Imperial Sugar processing facility. Haag engineers were asked to evaluate the scope and cost of damage, monitor the repairs, and segregate upgrades and improvements.

by John D. Stewart, P.E., Principal Engineer Emeritus

Around 7:00 am on February 7, 2008, a massive explosion occurred in the center of the Savannah Foods/Imperial Sugar facility, destroying or extensively damaging all three sugar silos and the packaging buildings that surrounded the silos. Sugar dust was believed to have been ignited by operating machinery. Many buildings outside the center of the plant also was extensively damaged. Investigations by government agencies as well as private experts concluded that the event was caused by an explosion of sugar dust followed by a fire wherein the sugar in the silos and throughout the area burned. Tragically, 14 individuals were killed in the blast and some 40 others were burned or injured.

Savannah Foods in Port Wentworth, Georgia, was founded in 1915 by Benjamin Alexander Oxnard and Richard H. Sprague when they moved their entire sugar refining operation, including more than 300 employees and their families, from St. Mary’s Parish in Louisiana to Port Wentworth. The refinery took in raw sugar and processed it into refined sugar and various other sugar products.  The Savannah Sugar Refinery began melting sugar on July 7, 1917.  In 1997, Imperial Sugar Corporation acquired Savannah Foods & Industries, Inc., which at the time was the second largest sugar refiner in the industry. Savannah Foods & Industries marketed its sugar under the Dixie Crystals® brand.

The Port Wentworth refinery included many large buildings, various tanks, and additional equipment for processing the sugar.  Sugar was brought into the facility by ship and sent out by rail, truck, and ships.  Among the facilities were three very large reinforced concrete silos located in the center of the packaging and storage area and used for storage of bulk refined sugar.  These silos, constructed in 1935, were approximately 130 feet tall by 40 feet in diameter arranged in an east-west line and were capable of holding about 3 million pounds of sugar each.  A large 4-story building to the north was the North Packaging Building.  Another 4-story building to the south was the South Packaging Building.  North and South Palletizing areas were to the west of the silos.  The main refining and raw sugar storage facilities were east of the silos.  Other buildings were south of the silo/packaging area.

Following the February 2008 explosion, Haag engineers were engaged by the insurers to evaluate the scope of damage and cost of repairs to the facility resulting from the event.  Haag also monitored the repair work during the several year period of restoration. Haag’s role beyond evaluation of the scope of damage was to monitor and separate extensive upgrades of the rebuilt facility from needed repairs. The extensive upgrades of the facility took it from an old processing unit to a state-of-the-art processing and packaging plant.

Haag engineers were on site from shortly after the explosion until the repairs were completed and the plant restarted in late 2009.  Haag was closely involved in the evaluation of the scope of damage.  Knowing that the facility would be extensively modified during the restoration it was critical to prepare a detailed scope of work including estimates of repairs for facilities that would not be rebuilt in kind.  Haag also was closely involved in all discussions about all changes, extensive upgrades, and reconfigurations of the facility to ensure that costs charged to the insurers of the facility were fair and represented the costs to restore an equivalent facility despite the many changes.

In summary, a massive explosion and ensuing fire destroyed the entire packaging and bulk loading facilities as well as damaging the sugar refining, electrical power and steam facilities, and storage warehouses and bulk silos. Haag engineers were called in to evaluate the complete scope of damage to the facility. Then, we developed detailed cost figures for in-kind restoration of the facility. Finally, we monitored restoration work during the two-year work period to segregate all upgrades and improvements included with the actual costs. Haag engineers were involved in evaluating damage to structural, mechanical, electrical, and process equipment.  Haag prepared detailed cost estimates for all phases of the work.

John D. Stewart, P.E., is Principal Engineer Emeritus at Haag Engineering Co. and served as Haag’s President for more than 30 years (1982 – 2014). Mr. Stewart has been with Haag Engineering Co. since 1969. His engineering expertise includes evaluating and determining the scope of damage and repair options following failures, including at industrial plants, oil refineries, chemical plants. He has analyzed electrical failures, lightning damage, and electronic and computer equipment failures.

Mr. Stewart graduated from the University of Texas at Arlington with a Bachelor of Science degree in Electrical Engineering. He is a licensed professional engineer in the states of Texas and Arizona, and a member of the Institute of Electrical and Electronic Engineers (IEEE), the American Institute of Chemical Engineers (AIChE), the National Fire Protection Association (NFPA), the International Association of Arson Investigators (IAAI), the National Society of Professional Engineers (NSPE), and the Texas Society of Professional Engineers.

BELOW, A 2008 IMAGE AFTER THE EXPLOSION AND A 2019 OBLIQUE IMAGE OF THE SAME AREA (IMAGES 1 & 2). THE CENTERS OF BOTH IMAGES COVER MOST OF THE AREAS OF MAJOR DAMAGE.

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2019-factory-damage
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Imperial-Sugar-Explosion_Case-Study_2

Log Home Residence Impacted by a Felled Tree

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Haag Engineers were asked to determine the extent of structural damage caused by a felled tree that landed on a log home, and to distinguish possible damage from construction defects and/or long-term conditions.

Haag Engineers were asked to inspect a log home to determine the extent of structural damage caused by a felled tree that landed on the dwelling. During our inspection, we were also asked to distinguished tree impact damage from other construction defects and/or long-term conditions.

The main level wall structure comprised logs that were approximately 6-1/2 inches tall by 8 inches wide, and the top and bottom edges were milled with a double tongue-and-groove surface. Logs interlocked at corners with a saddle-style notch. Gable wall- and roof-framing were conventionally framed with sawn-lumber. The owner was concerned that the tree impact damaged the roof and misaligned the walls, which in turn misaligned the respective windows and doors. We utilized our knowledge of wood-frame construction; the characteristics of logs in log-style construction; and our experience with the effects of long-term conditions on structures versus recent impact forces on structures to determine the extent of damage caused by the tree impact and separate out the long-term conditions.

Whether its log home construction, conventionally framed structures, or structures with engineered wood products, Haag Engineers can determine the cause and extent of damages related to storms, long-term conditions, constructions defects, building code compliance, etc.

Miami-Dade College Parking Garage Collapse

Parking-Guarge-Collapse

A six-level precast concrete parking garage collapsed during erection, resulting in multiple fatalities and injuries. Haag was tasked with determining the cause(s) of collapse and the cost of cleanup and rework.

Haag forensic engineers arrived on site of the collapse of a six-story precast concrete parking garage hours after the collapse.  While the site was in the midst of rescue operations by county fire search and rescue Haag was involved in structural evaluation of the existing structure with county officials, OSHA, and numerous other parties. Haag performed a 3D laser scan to preserve the scene before debris was moved for recovery operations to establish member locations and conditions. We quickly provided a cost estimate for repairs/reconstruction including project schedule impacts.”   We quickly provided an estimate for repairs including project schedule impacts.

Mining Dragline Collapse

Haag Engineers were asked to determine the cause of failure that led to overturning of a dragline and partial collapse into the mining pit.

Haag Consultants were asked to evaluate the sequence of events and conditions that led to overturning of a dragline used to remove stone blasted from the face of the mine pit.  Analysis included consideration of site conditions, the effects of previous blasting, excavation procedures, and the involved equipment.

Residence Struck by Lightning

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The metal chimney at a residence was struck by lightning during a severe thunderstorm. Major damage ensued.

A severe lightning strike hit a steel chimney cap and passed into a house in the North Texas area. Lightning entered the house through the metal chimney and was carried along corrugated steel gas tubing (CSST), copper electrical wiring, copper water piping, and the wooden structure itself.

The concussion broke gypsum drywall panels, burned electrical wiring insulation, damaged copper water piping, and melted multiple feet of CSST gas tubing.  Minor fires occurred in the house but were extinguished before the house suffered major fire damage.  Essentially all electrical and electronic devices in the house were damaged beyond repair.  Two quarter-size holes were melted in the chimney cap.  This was an early example of the dangers of lightning strike damage to a house utilizing CSST gas tubing.  Haag engineers were called in to assess the complete scope of damage.

Roof Collapse of Industrial Structure

Structural-Damage

Haag Engineers were asked to determine the cause of a partial roof collapse at an industrial facility.

The roof of a steel-framed industrial facility had partially collapsed in one location, and excessive deflections were reported at several additional locations. The owner attributed these conditions to the weight of ice and snow on the roof. Haag Engineers inspected this roof and noted extensive deterioration of the cold-formed steel roof purlins at the collapse from long-term roof leaks. Our failure and damage inspection also revealed non-standard connections of purlins where excessive deflection was reported. While the weight of snow on the roof triggered the collapse, the root cause was loss of structural capacity of roof purlins from long-term deterioration of building components due to roof leaks.

Sudden Soil Dropout Near Residence

Storm Drain

Haag was asked to conduct a residential structural damage investigation and evaluation related to ground subsidence claim.

A homeowner was concerned after a 6-foot diameter, 3-1/2-foot-deep hole (dropout) opened up in the back yard at the property line. Sinkholes are common in the Tampa Bay area. At the time of the evaluation, Haag Engineers observed that a stormwater catch basin was located at the street in the vicinity of the property line. Further investigation revealed that a concrete stormwater pipe ran under the side property line and that it lay directly beneath the dropout.  Soil had been washing into a hole in the pipe creating a void that eventually collapsed. The liability for correcting the problem shifted to the municipal stormwater utility.