Civil Engineering Challenges in Brownfield Projects - A Case Study

Expansion / Debottlenecking of Industrial or Oil & Gas plants is a common phenomenon and many a times such expansion has to be located within limited plot boundaries posing multiple challenges in locating the equipment and design & execution of supporting civil structures. In some cases, finalized supporting civil structures are not feasible to implement due to additional challenges such as additional underground utilities not identified in as-built survey that may arise during execution stage affecting project schedule. Generally, such unique design challenges are not encountered in Greenfield project development. This paper presents the typical constraints encountered in expansion projects, key parameters required to finalize the innovative solutions and measures / methods adopted to overcome the constraints in most effective and economical way in one of the major brownfield project without affecting safe functioning of existing plant. Vibration transmissibility to structures / equipment from new equipment or old equipment vice versa, physical constraints in supporting / routing new piping, underground utilities present in the plot are some of the major challenges faced during detail engineering. Enhancing existing supporting structures for new codal requirements (e.g. revised seismic definition) and enhanced design life to support additional loads of new project in addition to existing ones are some of the additional challenge faced during engineering and construction of the brown field projects Key parameters to be studied / considered while arriving optimal civil engineering solutions to challenges encountered, dynamic properties of new or existing equipment, foot print and founding details of existing foundations, underground utilities present in the plot / boundaries, presence of ground water table, execution feasibility of proposed new civil structures under plant operating conditions thereby avoiding plant or unit shutdowns etc. The solution arrived may have to be revised based on additional challenges that may unfold during execution stage. Fit for purpose supporting structure configurations, out of box structural designs, usage of unique material etc., are some of the methods adopted in arriving safe and economically sound design to overcome the constraints. Brownfield expansion in constrained plots of existing plants is a common phenomenon in all industries. Fit-for-purpose solution needs to be arrived considering constraints applicable to that equipment / plot while maintaining Plant safety and integrity. Similar approaches may be adopted to mitigate challenges in brownfield expansion of other plants to arrive at cost-effective & safe solutions.