Landfills are large and dynamic systems that can take several decades to develop. Unlike many other infrastructure projects that have a beginning and an end to the construction of the project, landfills constantly grow and change due to many factors, including but not limited to:
From an engineering perspective, it is very common to see changes to the engineering team over time. Each team brings about their ideas and preferences to the operator, and if they present technically competent and economically solid ideas, they can change the course of the landfill development. The course change could be shaped by what will get constructed, how it will get constructed, when it will get constructed, and what sequence it will get constructed. In most cases, the owner is in the loop, but the owner may not be intimately familiar with the nuances that such designs and modifications entail. Therefore, the owner may not necessarily realize hidden problems or mishaps that may happen in the future, which could be prevented by the engineer at an earlier stage of work.
Competent engineers starting work at an existing landfill site for the first time need to review years of data to become familiar with the history of the site before they can begin design work. The history of the site involves, but is not limited to, land use approvals, permitting, designs, modifications, environmental impacts, subsurface conditions, environmental improvements, leachate and gas collection and disposal, existing and future planned developments, operation requirements, and many other features that vary from site to site. Without such knowledge, the engineer is working in the dark without the owner’s knowledge that the engineer’s path lacks familiarity with details. Work products generated by an engineer with limited familiarity with the site are, at best, not reliable. Even potentially having significant impacts on the owner to fix issues that otherwise are preventable with sufficient due diligence.
For example, tasking an engineer to close a portion of the landfill, the engineer must investigate any plans set for landfill development, in the area planned to close. The engineer and owner can discuss any problems discovered by the engineer’s early due diligence, and solutions will be developed and adopted to address issues during the design. This level of due diligence provides the opportunity to generate sound designs and develops a level of confidence in the engineer in the mind of the owner.
SCS landfill design professionals train regularly to be thorough and comprehensive in their familiarization with a site. They spend significant effort to foresee potential problems that might arise many years down the road and find solutions for them now.
About the Authors:
Ali Khatami, Ph.D., PE, LEP, CGC, is a Project Director and a Vice President of SCS Engineers. He is also our National Expert for Landfill Design, Construction Quality Assurance, and Elevated Temperature Landfills. He has over 40 years of research and professional experience in mechanical, structural, and civil engineering. Dr. Khatami has been involved for more than 30 years in the design and permitting of civil/solid waste/environmental projects such as surface water management systems, drainage structures, municipal solid waste landfills, hazardous solid waste landfills, low-level radioactive waste landfills, leachate and wastewater conveyance and treatment systems, gas management systems, hazardous waste impoundments, storage tank systems, waste tire processing facilities, composting facilities, material recovery facilities, landfill gas collection and disposal systems, leachate evaporator systems, and liquid impoundment floating covers. Dr. Khatami has acquired extensive experience and knowledge in the areas of geology, hydrogeology, hydrology, hydraulics, construction methods, material science, construction quality assurance (CQA), and stability of earth systems. Dr. Khatami has applied this experience in the siting of numerous landfills.
William Richardson, EIT is Project Professional at SCS, and part of our Young Professionals organization. Will has two years of experience with landfill design projects, including permit modifications and siting requirements. He is currently working in Virginia Beach under the tutelage of Dr. Khatami.