His practice focuses on waste management and containment; disposal facility siting, design, permitting, and construction; design and permitting of landfill gas collection and utilization projects; hydrogeologic investigations and groundwater impact analysis and protection; remediation of contaminated sites; renewable energy projects; and construction management. As a consultant, Majdi has conducted geotechnical and hydrogeologic investigations and performed site suitability and feasibility evaluations for the remediation and closure of old solid waste disposal units and surface impoundments, development of new landfills on "greenfield" sites, and lateral and vertical expansions of existing landfills. He served as the project manager and engineer of record on numerous permit applications for coal combustion residuals (CCR) waste, hazardous waste, radioactive waste, municipal solid waste, and construction and demolition waste landfills. His designs involve alternative liner and cover systems and mechanically stabilized earth retaining walls.
Majdi was the engineer of record for more than 20 gas collection and control system (GCCS) design and phasing plans. He led investigations of landfill gas migration issues, performed GCCS trouble-shooting activities, and developed corrective action plans for several landfill sites. Majdi also prepared construction and bid documents for the construction of waste disposal facilities and landfill GCCSs, for the remediation of contaminated sites, and for the closure of old landfills and surface impoundments. Majdi has consulted on the development of several renewable energy projects, including landfill-gas-to-energy, solar, and waste-to-energy projects, and with emission reduction and carbon trading activities.
Majdi develops guidance manuals and performance standards on a wide variety of geotechnical topics related to solid waste management. Examples of these include "Assessment and Recommendations for Optimal Performance of Waste Containment Systems" for the U.S. Environmental Protection Agency; "Performance Standards of Landfill Covers" for the California Integrated Waste Management Board; and "Final Cover System Design Guidance" for the Maine Department of Environmental Protection. He has published 25 technical articles and technical guidance reports. He served as an editor of the international journal Geotechnical News and was awarded the 1994 American Society of Civil Engineers' Collingwood Prize.