August 28, 2019
In August 2017, Cajun Industries was approached by Burns & McDonnell to assist in a constructability study, as well as a budgetary pricing exercise for the new C5 Alkylation Unit at the Valero St. Charles facility in Norco, La. It did not take long to realize that the project would present a challenge for the Cajun team. The new Alky unit would be located inside the existing facility on a footprint that was barely larger than one acre in size. Nearly 800 14-inch by 90-foot-long precast concrete piles were scheduled to be installed in a space that measured roughly 200 feet long by 200 feet wide.
At this point of the project's life, the engineering was in the early phases. The project team, composed of Burns & McDonnell and Valero employees, knew the unique and challenging project would present many obstacles along the way. Approximately eight months before the project began, Burns & McDonnell reached out to Cajun and began discussing the many possible strategies for execution.
The design for the new Alky Unit involved large foundations ranging from five to nine feet below the existing grade. Cajun's Deep Foundations Unit along with Cajun's Baton Rouge Civil Business Unit worked together to present two different options for the project. The plan was simple either drive piles first or dig first. Given the poor soil conditions in south Louisiana, the decision was made to install piles from existing grade using a pile follower to reach design top of pile elevation. In addition to this execution strategy, Cajun used its sheet pile design abilities to engineer and install sheet piling around three of the four sides of the project footprint. The sheet pile retaining system would allow the foundations to be excavated safely without undermining the adjacent roads.
Challenges and solutions
As Cajun prepared to mobilize the project, the team began putting together a plan to work safely and efficiently while operating in such a small area. Surrounded by roads on three sides and an operating unit on the other, the only laydown room Cajun had available was the project footprint itself. It was recognized very quickly that storing full length 90-foot precast concrete piles would not allow for much maneuverability. Additionally, Valero's safety policy states that contractors must pre-drill any pile locations that are within the length of the pile to prevent damage to adjacent structures.
At this point, it was very clear that two-piece, spliced concrete piles would be necessary to execute efficiently. By utilizing spliced piles, the project team was able to reduce crane size as well as cut the required laydown area in half. Cajun solicited Boykin Brothers for the fabrication of the precast piles on the project. Together, they were able to utilize two different splices. Since not all piles carried a load in tension, a common drive fit compression splice was used on approximately 20 percent of the piles, saving the project time and money. The remainder of the piles carried a tensile design load. These piles would be cast using the Liemet Tension splice. The Liemet splice provides a cost effective solution without spending excessive time and energy to get the job done. Four pins, one at each corner, delivers a reliable connection that is strong enough to bear almost any tensile load.
Scope of work
The Valero Refining C5 Alkylation Project provided an opportunity for Cajun to showcase multiple facets of its pile installation abilities. After successfully installing six probe piles and performing dynamic testing on each, a static test pile location was determined. After installing the four reaction piles and erecting the test frame, Cajun switched gears to sheet piling while the 14-day load test setup time ensued.
Cajun was tasked with providing a stamped design engineering package to install sheet piling on three of the four sides of the project. Knowing the foundation placement would require deep excavations along with the heavy road traffic that took place just on the other side, Cajun implemented the temporary retaining system approach. After the design was approved by Burns & McDonnell engineering, the project team began procuring and installing over 150 pairs of sheet piling. Cajun worked together with Skyline Steel to develop a plan consisting of multiple custom corners and almost 700 wall feet of NZ-19 hot rolled sheets.
Just as Cajun was completing the sheet piling installation, the test pile program was complete and it was time to enter into production. Cajun began installing production piles in mid-July 2018 with a target completion date of Oct. 31 Cajun successfully installed the 797th precast concrete pile exactly on Oct. 31. The execution by the project team was nearly exactly as planned. Battling the south Louisiana summer rainstorms coupled with extreme temperatures, Cajun performed day in and day out completing the project on time and with zero injuries.
Cajun's number one priority is the safety of its employees. The company's goal is to foster an atmosphere where employees are confident in their safe return home each day. Cajun instills a safety culture that allows everyone to feel comfortable stepping up to recognize and correct any unsafe conditions or hazards that may arise. This was consistently displayed by field employees exercising their stop work authority to prevent hazards before they became an incident. On a more detailed level, Cajun uses a mentoring program where any employee that has been with the company for less than 90 days is assigned an experienced mentor who is responsible for coaching and instilling the Cajun safety culture in new personnel. The mentorship program allows all Cajun employees to grow and succeed in their new position.
In addition to the deep-rooted Cajun culture, the project teams implement a well-funded incentive program for its craft level employees. Each employee received a gift for a job well done at the end of the project. These gifts included monthly project safety lunches, along with the end-of-project gifts like power tools, fishing gear, iPads, outdoor cookers and big screen TVs!
In the end, Cajun was commended by Burns & McDonnell and Valero for completing a successful and safe project. The Valero C5 Alky project was a true testament to Cajun's continued excellence in construction.